The Rev. Frank Schaefer did not hesitate for a moment when asked by his gay son, Tim, to preside at his wedding in Hull. The Methodist minister was honored — and overjoyed.

Last week, six years after the ceremony, Schaefer was convicted at an emotional church trial in Pennsylvania for breaking church laws that forbid United Methodist clergy from performing same-sex weddings. The jury imposed a 30-day suspension, and told Schaefer that if he could not comply with church law, he must surrender his credentials as a clergyman.

“Absurd? Prehistoric?” said the Rev. Robert Coombe, who represented Schaefer in the trial, searching for words to describe his view of the proceedings. “Nobody wants a trial. It’s very painful to everyone involved, and it’s costly to the church, so why are we doing this?”

Schaefer’s is one of a number of similar cases making their way through the legal system of the United Methodist Church, exposing a sharp rift within the nation’s second-largest Protestant denomination — and raising questions about whether it can remain intact.

“A house divided cannot stand,” said John Lomperis, the United Methodist director at the Institute on Religion and Democracy, which supports traditionalist positions on Scripture and church law. “Currently within the United Methodist Church, we have people with fundamentally irreconcilable differences about not just issues of sexual morality, but basic core beliefs.”

Days before the Schaefer trial, the church’s Council of Bishops — all the church’s active and retired bishops — requested that a formal complaint be filed against retired Bishop Melvin Talbert, who performed a wedding ceremony for a gay couple in Alabama in October. (The couple had already married in Washington, D.C., where gay marriage is legal, but wanted a church ceremony back home for friends and family, according to the Birmingham News.)

Schaefer Family via Associated Press

The Rev. Frank Schaefer didn’t hesitate when asked by his gay son, Tim, to preside at his wedding in Hull.

The Rev. Thomas Ogletree, retired dean of the Yale Divinity School, may soon face a church trial for officiating at the wedding of his gay son.

‘I cannot express to you how sad this makes me — even embarrassed — about my denomination.’

The Rev. Steve Heiss, a pastor in Binghamton, N.Y., who presided at the wedding of his lesbian daughter in 2002, and who has performed a number of same-sex couples’ weddings since, also may face prosecution.

And the Rev. Sara Thompson Tweedy, a community college dean and part-time pastor in White Plains, N.Y., is the target of a complaint for being a married lesbian.

Some clergy — particularly in the Northeast — are in open rebellion, performing gay marriages in defiance of church law. In a show of solidarity with Schaefer, who leads a church in Lebanon, Pa., several dozen Methodist clergy jointly presided at a same-sex wedding in Philadelphia last month. Nearly 200 clergy in New England have signed a statement saying they would offer the church’s blessing to “any prepared couple desiring Christian marriage.” The Harvard-Epworth United Methodist Church, next to Harvard Law School, recently declared it would open its doors for same-sex weddings and support its pastor if he officiated at one.

“If you look at Facebook and local newspapers, I think you’ll see gay marriages [performed by Methodist clergy] are happening in Massachusetts and around the country,” said Alexx Wood, director of communications for the New England Conference.

The church’s law book, the Book of Discipline, declares that all people have sacred worth, but it calls the practice of homosexuality “incompatible with church teaching,” prohibits “self-avowed practicing homosexuals” from serving as clergy, and forbids clergy from officiating at same-sex unions.

But many United Methodists say that language contradicts another principle of the Book of Discipline: that the church and its ministries be available to everyone.

“On the one hand, we guarantee the blessings of the church to all people, and on the other hand we say that there are some people who do not receive those blessings because of their sexual orientation,” said the Rev. Leigh Dry, pastor of the Lexington United Methodist Church. “I cannot express to you how sad this makes me — even embarrassed — about my denomination.”

The New England Conference, which has more than 90,000 members, has voiced support for removing that language, as have other regional conferences in the United States. But the church’s global legislative body, the General Conference, has rejected changes to its stance on homosexuality at every quadrennial assembly since 1972.

While some other Protestant denominations — including the United Church of Christ, the Unitarian Universalist Association, and the Episcopal Church of America — have liberalized their rules on gay clergy and gay marriage, the United Methodist Church appears to be moving in the opposite direction. The margin of vote against changing the church’s stance on homosexuality to a non-judgmental one, 61 percent to 39 percent, was wider at the 2012 General Conference than in 2008.

The United Methodist Church’s distinctive structure accounts for its divergence from the other mainline denominations on gay issues. It is a “connectional” church — a network of congregations that are interdependent, with a common mission and set of laws — with significant membership outside the United States.

Its centralized lawmaking body, the General Conference, is made of up of delegates from around the world, assigned roughly in proportion to lay members and clergy in each geographic region. Almost one-third of the delegates now come from Africa, where homosexuality is widely considered immoral, if not illegal.

This is very different from the structure of the Anglican Communion, “a kind of loose federation of churches with a shared Anglican tradition,” said Robert C. Neville, professor of philosophy, religion, and theology at Boston University and former dean of its School of Theology and Marsh Chapel.

That “loose federation” allows the different Anglican churches across the world some autonomy — so, for example, the Episcopal Church of America was able to confirm a gay bishop in 2003 despite the strong opposition of African Anglicans, who had no say in the vote.

The United Methodist Church, on the other hand, has “a very strong federal government,” Neville said. “The General Conference makes rules for everything, and makes them by a majority vote.”

And the power of conservatives appears to be growing in the United Methodist Church, fueled by demographic shifts in church membership. Between 2009 and 2012, the church in the United States lost nearly 300,000 of its 7.7 million members — with the heaviest losses in the more liberal regions of the country, such as New England — while gaining more than twice that in sub-Saharan Africa, Lomperis said.

Frustrations on both sides are coming to a boil. At last year’s General Conference, an African delegate likened homosexuality to bestiality; later, a group of pro-gay Methodists disrupted the proceedings by rushing the floor and singing a hymn.

“The United Methodist Church is falling apart,” said Will Green, the pastor of St. Nicholas United Methodist Church in Hull, where Schaefer’s son Tim attends church. “Even in the past couple of weeks, meeting by meeting, event by event, it is coming undone.”

Some who support the church’s position on homosexuality agree.

“Further conversation is not going to resolve the division in our church,” said the Rev. Thomas Lambrecht, vice president of Good News, a Methodist ministry that promotes orthodox viewpoints, and who advises the church prosecutor in the Schaefer trial. “Especially when people who favor the performing of same-sex weddings are defying church policy.”

Many who want the church’s rules to change say the denomination’s only hope of staying united is to allow local jurisdictions more autonomy. But the General Conference soundly rejected a proposal that church members “agree to disagree” on homosexuality in 2012.

Another possibility, Neville said, is for the American jurisdictions to separate from the international jurisdictions. Or, he said, the church could split along ideological lines, as it did over slavery in 1844 — a divide that took a century to repair.

Still another possibility: Those who want the church to change its laws on homosexuality could decide to wait it out. Over time, Neville said, a new generation of Methodists in the southern United States will replace their more conservative elders, and the American delegation might become more unified in favor of changing the homosexuality rules.

Then again, he said, some who want change might get tired of waiting and just leave the church.

As a sense of crisis mounts, leaders are trying to defuse tensions.

Bishop Sudarshana of the New England Conference wrote to local members last week expressing his disappointment with the Schaefer verdict and the bishops’ decision on Talbert, but promising to “uphold the Discipline of the church with integrity.” Acknowledging differing views within the church, he urged continued dialogue.

“Let us all continue to pray for perseverance and for justice to prevail for all of God’s children everywhere,” he wrote.

The Rev. Thomas E. Frank, a historian at Wake Forest University and an expert on Methodist polity, sent an open letter to the bishops asking them to stop the trials while the church talks through its differences.

“At the moment, we have the prospect of church trials for at least two different ordained elders who performed such ceremonies for their own beloved children. Really?” he wrote.

Frank called the trials “a disgrace to our heritage.”

“It is divisive, bringing interference from outside groups . . . and introducing the language of ‘prosecution,’ ‘defense team,’ ‘conviction,’ ‘judge,’ and ‘jury,’ to our church as if we were all players in ‘Law and Order,’ ” he wrote.

It remains unclear how the bishops will respond. In the meantime, however, the crisis threatens to escalate. Schaefer’s case is not quite over.

His trial featured emotional testimony from his son, who spoke of how he contemplated suicide as a teenager, fearing rejection by his parents and his church. People came from across the country to watch the proceedings.

Schaefer says he will continue to perform gay weddings; he says he now sees himself as an advocate for gay, lesbian, bisexual, and transgendered people.

The Rev. Scott Campbell, a Harvard University chaplain and pastor of the Harvard-Epworth church who has advised Schaefer and others facing trials, said Schaefer could appeal his case on the grounds that there were “several serious legal errors” in the decision.

He and Schaefer are also mulling whether the jury’s decision may leave room for Schaefer to follow his conscience, yet remain a clergyman. Schaefer suggested, for example, that he might be able to transfer to another conference that is more accepting of his views.

But Lambrecht, who helped the church prosecute Schaefer, said the trial’s outcome was clear: Schaefer must observe the church’s rules on homosexuality if he wants to keep his credentials. “I don’t see any ambiguity in the penalty,” he said.

Schaefer said he has been buoyed by a tide of messages of support; a “Stand with Pastor Frank” Facebook page already has more than 10,000 “likes.”

And his son sees a silver lining to the case, which drew national media attention.

“The more pressure that is put on the church with the publicity,” Tim Schaefer said, “the less likely it is that they’re going to be able to deny having that conversation about where we go next with LGBT rights within the church.”